<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<style>
	body,p{margin: 0;}
	h2{margin: 0;font-size:100%;}
	ul{margin: 0;padding: 0;list-style: none;}   
	a{text-decoration: none;color:inherit;}
	.box{width: 572px;border: 1px solid #999;overflow: hidden;}
	.nav{margin-left: -1px;font: 14px "微软雅黑";overflow: hidden;background-color: #f1f1f1;}
	.navI{float: left;width: 33.333%;box-sizing: border-box;}
	.navI-tit{line-height: 40px;text-align: center;cursor: pointer;border-left: 1px solid #cecece;border-bottom: 1px solid #cecece;}
	.navI-txt{width: 572px;height:200px;text-indent:2em;line-height: 2;background:#fff;}
	.ml1{margin-left: -100%;}
	.ml2{margin-left: -200%;}
	.navI_active{position:relative;z-index:1;}
	</style>
	<body>
		
		<div class="box">
		    <ul class="nav">
		        <li class="navI navI_active">
		            <h2 class="navI-tit">课程</h2>
		            <p class="navI-txt">课程内容</p>
		        </li>
		        <li class="navI">
		            <h2 class="navI-tit">学习计划</h2>
		            <p class="navI-txt ml1">学习计划内容</p>
		        </li>
		        <li class="navI">
		            <h2 class="navI-tit">技能图谱</h2>
		            <p class="navI-txt ml2">技能图谱内容</p>
		        </li>
		    </ul>   
		</div>
		
	</body>
</html>